```ts
// Button.stories.tsx

import React from 'react';
import { Story, Meta } from '@storybook/react';
import Button from './Button';

export default {
  title: "Button",
  component: Button,
  argTypes: {
    backgroundColor: { control: 'color' },
  },
  args: {
    // Now all Button stories will be primary.
    primary: true,
  },
} as Meta;

```